Curvature and gradient drift effects on trapped-electron modes

Journal Article · Wed Oct 01 04:00:00 EDT 1980 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.862875· OSTI ID:7183199

Crystal, T L; Denavit, J

Computer simulations of local trapped-electron modes in toroidal plasmas, including curvature and gradient drift effects, are presented. These simulations are based on the linearized electron drift-kinetic equation, Fourier transformed with respect to the poloidal and toroidal angles. No a priori distinction is made between trapped and circulating particles, and collisions are represented by a Lorentz model giving pitch-angle diffusion. A series of computations shows the dependence of the growth rates on rho/sub e//r and on ..nu../sub ef//..omega../sub asterisk/ (rho/sub e/ is the thermal electron gyroradius, r is the flux surface minor radius, ..nu../sub ef/ is the effective collision frequency, and ..omega../sub asterisk/ is the drift wave frequency). For ..nu../sub ef/< or approx. =0.5 ..omega../sub asterisk/, strong drift resonance effects are observed, but these are destabilizing only for rho/sub e//r below a critical value. These growth rates decrease rapidly for collision frequencies ..nu../sub ef/> or approx. =..omega../sub asterisk/. For ..nu../sub ef/>>..omega../sub asterisk/, the dissipative trapped-electron instability occurs. In this regime, curvature and gradient drifts are stabilizing; Landau damping due to resonant circulating electrons reduces the growth rates and significantly modifies the mode structure of the dissipative trapped-electron instability.

• Research Organization: Department of Mechanical and Nuclear Engineering, Northwestern University, Evanston, Illinois 60201
• OSTI ID: 7183199
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 23:10; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700108* -- Fusion Energy-- Plasma Research-- Wave Phenomena
ANALYTICAL SOLUTION
ANNULAR SPACE
COLLISIONS
COMPUTERIZED SIMULATION
CONFIGURATION
DAMPING
DIFFUSION
DISPERSION RELATIONS
DISTRIBUTION FUNCTIONS
ELECTRON PLASMA WAVES
ELECTRONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
FOURIER TRANSFORMATION
FUNCTIONS
INSTABILITY
INTEGRAL TRANSFORMATIONS
KINETIC EQUATIONS
LANDAU DAMPING
LEPTONS
PLASMA INSTABILITY
PLASMA SIMULATION
PLASMA WAVES
SIMULATION
SPACE
TOROIDAL CONFIGURATION
TRANSFORMATIONS
TRAPPED ELECTRONS